Field of the Invention
The invention relates to a medical prosthesis (Class 623), and in particular a clip for plicating the posterior leaflet complex of tissue, including methods for reducing the annular size of a tricuspid valve in a heart by mounting a clip or tissue anchor onto the posterior leaflet complex of tissue (leaflet, annulsu, chordae) to bicuspidize the triscuspid valve.
Description of the Related Art
Tricuspid valve regurgitation occurs when the tricuspid valve leaflets do not close, coapt, properly during systole. Systole is the contractive phase of the heart and diastole is the filling phase. When the right ventricle is contracting and pumping blood to the lungs, the right atrium is filling, and the tricuspid valve in healthy individuals is closed. When a patient has heart disease or damage, a condition can occur called right ventricular dilatation, which when the right ventricle moves outwardly away from the septal wall, i.e. to the left when viewed from the front of a patient. As a consequence of right ventricular dilatation (RVD), the tricuspid valve leaflets become deformed from their normal positions, and the valve does not close completely, causing blood that is pumped during ventricular systole to be partially ejected back into the right atrium: regurgitation.
Efforts to treat tricuspid regurgitation have included deploying a tricuspid prosthetic valve substitute. However, prosthetic tricuspid valves have at least the same type and degree of complications as in the aortic and the mitral positions, namely an increased incidence of thrombo-embolic phenomena, mechanical degeneration, valve dysfunction from tissue ingrowth. Only about 35-45% of the patients were alive free from reoperation after tricuspid valve replacement.
Another effort, DeVega, developed a procedure which consists of folding and stitching, also called “plication”, of the posterior and anterior portion of the annulus, preserving the septal portion, with a double continuous suture. However, the sutures may pull out of the tissues, a phenomena called dehiscence. A variation of this procedure is to use a clip (Trialign®) to grab and cinch all three leaflets with an implanted, free-floating, permanent clip. The use of Teflon pledgets in each bite of the suture has reduced the incidence of tissue rupture, and the use of polyester fabric covering to promote tissue in-growth for the clip reduces the incidence of leaflet tearing and rupture, but both of these can cause the valve to become stenotic. Also, there is a large risk of device detachment when using surgical anchors on tissue that is as delicate and thin as the tricuspid leaflets.
Another effort to treat tricuspid regurgitation includes deployment of an annuloplasty ring. An annuloplasty ring is a rigid, horse-shoe shaped ring that is sewn onto the fibrous tissue at the top edge of the tricuspid valve, effectively mechanically forcing the valve annulus back to a crown shape so that, in theory, the leaflets hanging below the annulus will again coapt. The ring cannot be a complete circle since there exists a section of the fibrous annular tissue that is involved in electrical conductivity, called the atrio-ventricular node (AV node), which is within a highly sensitive section of tissue called the “Triangle of Koch”. This section of the tricuspid annulus, above the septal leaflet, is known by surgeons and practitioners as a section that must be surgically avoided since interventions there are known to disrupt heart function. However, deployment of an annuloplasty ring is an open heart surgical procedure and therefore includes all of the attendant problems of open heart surgery, such as infection, recovery from traumatic opening of the chest wall, embolism, problems associated with use of a heart-lung bypass machine, age-related and condition-related appropriateness of invasive surgery, and other complications.
Accordingly, there exists a need for percutaneous tricuspid valve repair that addresses one or more of the problems in the prior art.